Pointer in C++ hackerrank solution

      
  #include <iostream>
  using namespace std;
  
  void update(int *a, int *b) {
      int sum = *a + *b;
      int diff = abs(*a - *b);
      
      *a = sum;
      *b = diff;
  }
  
  int main() {
      int a, b;
      cin >> a >> b;
      
      int *ptr_a = &a;
      int *ptr_b = &b;
      
      update(ptr_a, ptr_b);
      
      cout << a << endl;
      cout << b << endl;
      
      return 0;
  }
   

Let's break down the code and explain each part:

#include : This preprocessor directive includes the necessary input/output stream library for C++.

using namespace std;: This statement allows us to use the standard library functions without explicitly specifying the namespace (e.g., cout, cin).

void update(int *a, int *b) { ... }: This is a function named update that takes two integer pointers (a and b) as arguments and returns void (i.e., no return value). Inside the function, we create two variables sum and diff. We calculate the sum of the values pointed to by a and b, as well as the absolute difference between them. Then, we update the values pointed to by a and b with the calculated sum and difference, respectively.

int main() { ... }: This is the main function of the program. It is the entry point for execution.

int a, b;: We declare two variables a and b to store the input values.

cin >> a >> b;: This statement reads two input values from the user and assigns them to the variables a and b using the >> operator.

int *ptr_a = &a; int *ptr_b = &b;: We declare two integer pointers ptr_a and ptr_b and initialize them with the addresses of variables a and b, respectively. The & operator is used to get the address of a variable.

update(ptr_a, ptr_b);: We call the update function and pass the addresses of variables a and b as arguments. This allows the function to modify the values of a and b indirectly by dereferencing the pointers.

cout << a << endl; cout << b << endl;: These statements output the updated values of a and b using cout. The << operator is used to print the values.

return 0;: This line indicates that the program execution is successful and returns the value 0 to the operating system.

When you run this program, it will prompt the user to enter two values (a and b). It will then call the update function, passing the addresses of a and b. The function will modify the values of a and b indirectly through the pointers. Finally, the updated values of a and b will be displayed.

To use this code in HackerRank's "Pointer" problem, you can copy and paste it into the editor and submit it. The program will prompt the user for input, and the output will be displayed in the output window or terminal, depending on the HackerRank environment.

Make sure to read the problem statement and input/output requirements carefully and adjust the code accordingly if needed.